Drilling device



May 17, 1960 c. T. THOMPSON DRILLING DEVICE 3 Sheets-Sheet 1 Filed Jan. 2, 1959 GI M 5 0 H m7 .1 S w M H G HIS ATTORNEY y 7, 1960 c. T. THOMPSON 2,936,637

DRILLING DEVICE Filed Jan. 2, 1959 s Sheets-Sheet 2 INVENT'OR CHARLES 7. THOMPSON HIS ATTORNEY May 17, 1960 O c. T. THOMPSON 2,936,637

DRILLING DEVICE Filed Jan. 2, 1959 3 Sheets-Sheet 3 9 65 B 9 75 37 95 C II 25 2I27 ll 0 F/6.6

95 99 L./-/. ROTATION Ill 23 IO A 9 8| SLIP ROTATION Ill 8| A ,e3 73 33 73 FIG. 8 INVENTOR CHARLES 7. THOMPSON BY 1 99 R. H. H0 H1 r/o/v M 9' I29 ms ATTORNEY DRILLING DEVICE Charles T. Thompson, Asbury, N.J., assignor to Ingersoll Rand Company, New York, N.Y., a corporation of New Jersey l Application January 2, 1959, Serial No. 784,522 1 Claims. c1.14-1s7 nit States Patent O the head. 'The teeth of the ratchet are disposed at the solid mineral, such as rock, it has been found necessary to rotate the drill, usually a star drill, on its axis so that the star point thereof shall come into engagement with different angularly spaced portions of the rock at the end of the hole being drilled. Heretofore various devices have been proposed for effecting increments of rotation during the drilling operation concomitantly with the usual rapid reciprocating movement of the impact member along its axis. For this purpose a rifle bar has been used the helical rifling of which is engaged by a key element movable axially with the reciprocating impact producing member of the drill. The impact member also engages the drill steel chuck mechanism in such a manner as to provide relative axial movement and prevent relative rotational movement therebetween. Thus, there is concomitant relative rotary motion between the rifle bar and the drill steel with the reciprocatory axial movement of the impact member. If the rifle bar is not held against rotation, the resistance to movement of the drill steel in contact with the ground will be greater than the resistance of the rifle bar and the rifle bar will provide the relative rotational movement concomitant with the axial movement of the impact member. against movement, the drill steel then rotates. Reciprocation of the impact member may be affected by a piston in a fluid pressure cylinder. A ratchet and pawl device has been used in combination with such a rifle bar .for effecting rotation of the drill. Rotation in either direction about the axis has been secured with a rifle barhaving a given, left or right, inclination of its helical contour by means of a ratchet and pawls exterior to the ratchet to provide for rotation in one direction or the other concomitantly with the reciprocating movement of the impact member.

It is an object of the invention to provide in such a drilling device a compact construction for securing rotation of the drill selectively in either direction about the axis.

-It is another object of the invention to provide in such a drilling device for selective rotation of the drill and alternatively for not causing rotation of the drill in either direction during the drilling operation.

It is a further object of the invention to provide in a drilling device of this type for the selective rotation in either direction and, when desired, for slip rotation of the drill with respect to its supporting housing.

.It is a feature of the invention that a head which may be formed as an enlargement of or otherwise may be connected to the rifle bar is provided with a periphery extending about the axis of the drill. This head carries If the rifle bar is held inner periphery of the ring adjacent the periphery ofthe head. One of the pawls is supported in the head so as to provide for unidirectional rotation of the head relative to the ratchet ring in a given direction and to prevent rotation in the reverse direction when this pawl is in engagement with the ratchet ring teeth. The other pawl is supported in the head so as to provide for unidirectional rotation of the head relative to the ratchet ring; in the reverse direction and to prevent rotation in the given direction upon engagement of this other pawl with the ratchet ring teeth. Preferably these two pawls respectively are pawls of two sets of pawls disposed in spaced relation to each other along the axis, the pawls of each set being disposed about the axis and supported by the head for movement with respect to the head into and out of engagement with the teeth of the ratchet ring.

It is another feature of the invention that means are provided being operatively connected to the pawls of the two sets for selectively effecting disengagement and engagement of the pawls of the two sets from and with the ratchet teeth so as to provide for rotation of the head the drill structure and extending about the periphery of relative to the ratchet selectively in the two directions about the axis. The means referred to preferably are provided by rings each of which is associated with one of the sets of pawls and is capable of engaging all of the pawls of that set. This means also provides for effecting movement of the rings associated with the respective sets of pawls along the axis into and out of engagement with the pawls for effecting disengagement of the pawls of one set to release the ratchet so as to provide for rotation of the head in a selected direction. Movement of the ring associated with the other set of pawls may be effected to provide for rotation of the head relative to the ratchet in the reverse direction. Operation of these actuating rings also may be effected to release both sets of pawls to permit rotation of the head in both directions thus no rotation is imparted to the drill.

With these and other objects in view, the nature of which will be more apparent, the invention Will be more fully understood by reference to the drawings, the accompanying detailed description and the appended claims.

Fig. 1 shows partly in elevation and partly in longitudi nal section a rock drill constructed in accordance with this invention;

Fig. 2 is a section on line 22 of Fig. 1;

Fig. 3 is a section on line 3-3 of Fig. l;

Fig. 4 is a perspective view of a pawl which is capable of cooperating with the ratchet in the device of the invention;

Fig. 5 shows an actuating ring for effecting disengagement and engagement of the pawls; Fig. 6 shows a control device in the position for determining the settings of the actuating rings to secure rotation of the drill in a given direction;

Fig. 7 shows the control device in the position for determining engagement of the actuating rings with both sets of pawls to release the ratchet for no rotation;

Fig. 8 shows the control device in the position for determining the settings of the actuatin rings to secure rotation in the reverse direction from that of Fig. 6..

This invention, as illustrated, is embodied in a reciprocating pneumatic motor drivenrock drill, the drill bit of which can be positively rotatedin either direction or set for no rotation. V V r Fig. 1 shows a rock drill 10 having a housing 11 of generally cylindrical form providing a cylinder 13 in which a piston, not shown, is disposed for movement to and fro along the axis of the cylinder to deliver conve'ntionally the rapidly repeated impact to a star drill, not

shown, supported in the casing 15.

conventional manner to effect rotation of the drill. In the embodiment being described the rifle bar 17 is provided with a head 21 which 'is formed as an enlargement v of the rifle bar at an end thereof and which isprovided with a generallyicylindrical periphery 23. In 'this e-mbodiment the head is also provided with face s, 2 5 27 which are transverse to the axis of the rifle bar and which extend outwardly from the rifle bar to the pe riphery23 of the head. v Extending about the periphery of the head 21 is a ring 31 which is provided at its inner peripheral surface with ratchet teeth 33 disposed closely adjacent but with clearance with respect to the periphery 23 of the head. The ratchet ring 31 is supported in position with respect to the head by members 35, 37 which are of annular form and carry and permit rotation of the hub portions 39, 41 which extend along the axis from the head 21. The members'35, 37 are provided with shouldered portions outwardly thereof for engagement with the axially spaced ends of the ratchet ring 31. The head 21 together with the rifle bar thus may rotate relative to the members 35, '37 and relative to the ratchet ring 31. Suitable packing means is disposed in the annular groove 43 and engaging hub 39 toconfine a fluid pressure medium within the cylinder 13 from escaping along the hub 39. Other packing means will be referred to hereinafter.

In the head 21 between the two transverse surfaces 25, 27 thereof sockets 45 of cylindrical form are provided, as shown in Fig. 3', in which pawls 46 of the form: shown in Fig. 4 are disposed, these pawls having a generally cylindrical portion 47 from which extends the. pawl blade 49 providing a teeth engaging edge portion. 51.,v Blade 49 of each pawl extends into a space. 53 'formed' in the head 21 adjacent its periphery, this space providing for pivotal movement of the pawl on the axis ofv the socket into 'and out. of engagement with the teeth 33 of the ratchet 31. I

It will be noted that two sets of pawls are provided, one with the, blades extending from thesockets 45 in a clockwise direction with respect to the axis into the respective recesses 53, the other set of pawls having its blades 49 extending in the opposite direction into the corresponding recesses 53.

theratchet, that movement of the head with respect to the ratchet is prevented in the direction inwhich the pawls extend and that movement is permitted in the other direction. Selective rotationmay be secured when one or the other sets of pawls, by means tobe described, is held out'of-engagement with the ratchet teeth 33' and the other set of pawls is released for engagement. with these teeth. v

For effecting such, engagement each, pawl is provided with a compression spring 57 disposed in a hole 59 drilled in the head 21. This compression spring 57engages a cap-like member 61 'slidably disposed in,the hole 59 and at its rounded outer end engaging theinner face 52 of the blade 49. The blade 49 thereby is biased outwardly with respect tothe axis of the drill into engagement with the ratchet teeth 33. Fig. 3 shows the pawls 46 and their correspondin'g springs 57 and cap-like mernbers 61 that are disposed at the left hand side of the'head 21 in Fig. 1. The cap-like members 61 are shown partlyqin dotted outline for the pawls at the right, hand side ofjthe headiin Fig. 1,' the springs being omittedfor clearne-ss. It. will beunderstood, having regard to the form of the pawl 46 shown in Fig. 4, that the cylindrical parti47 of this pawl which fits in the socket: 451:, extends, through the head parallel to'the axis and between the opposite faces. 25, 27 of the'head'. The members 35, 37 that are It will be understood, when the blades ofone set are engaged with the teeth 33 of disposedin engagement with these transverse surfaces 25, I

The ratchet ring 3 1 and the two members 35, 37 are formed with shoulder portions which provide cylindrical surfaces 63 on the ratchet ring and cylindrical surfaces 65 on the head 21 that are concentric on the axis of the drill. These cylindrical surfaces 63, 65 form therebetween annular fluid pressure spaces adjacent the ends of the ratchet teeth in eachof which is disposed an actuating ring 67, each ring 67 providing an inner cylindrical surface in sliding engagement with one of the cylindrical surfaces 65 formed on the members 35, 37. The actu-- 'ating rings" 67 also provide outer cylindrical surfaces which may engage an inner cylindrical surface on the ratchet ring 31. adjacent the ends of the teeth 33. It will be undersood that the actuating ring 67, therefore, may move in sliding bearing relation to the cylindrical surfaces which have been mentioned toward and away from the ratchet teeth 33. The ends of the actuating rings 67 may be beveled, as shown in Figs. 6, 7 and 8, for engagement with the blades 49 of the pawls of the sets that respectively are disposed at the adjacent transverse faces 25, 27. The bevel on the actuating ring 67' is so formed that when the actuating ring is moved toward the ratchet teeth 33, it will come into engagement with the pawls of the adjacent set and p-ivotally move these pawls inwardly in Fig. 3 to disengage them from the teeth 33 of the ratchet ring. When the actuating ring is reversely moved axially away from the ratchet teeth, the, adjacent pawls are disengaged from the actuating ring and, under the bias of the springs 57, are moved again intoengagement with the ratchet teeth.

As shown in Fig. 5, the actuating ring 67 carries at its outer periphery a pair of annular ribs 69 spaced apart in the direction parallel to the axis. These ribs serve to confine therebetween a packing ring 71, Figs. 6, "7' and 8, which is of such size as to be somewhat compressed when in place to provide against leakage of the fluid pressure medium along the surface 63 from the annular fluid pressure space in which such. actuating ring is disposed. Additional packing rings 73, 75 are provided at their respective cylindrical surfaces of the acuating ring and respectively in shoulders of the ratchet ring and in grooves in the members 35, 37 to seal against leakage of the fluid pressure medium along the actuating ring into the space about the head 21 .in which the ratchet teeth 33 are disposed. The actuating rings and their ribs, to-

'gether with the packing rings 71,. therefore, act as pistons when thefluid pressure medium is introduced into the annular fluid pressure spaces defined by the surfaces 63, 65 at the respective sides of the ribs 69 and the packing rings 71. Movement of the actuating rings along the axis thus may be effected in the directions respectivelyto bring the, actuating rings 67 into engagement with the pawls 460i the respective adjacent sets and to movethese actuating rings out of engagement with'these pawls. v V

Inforder to control the movements of the actuating rings 67, as shown somewhat diagrammatically in Figs. 6, 7- and 8, valve means are provided which is connected by conduits 81, 83, 85,37 to the fluid pressure spaces that are formed at either side of the pistons which are constituted by the packing rings 71 disposed between the ribs 69 of the actuating rings. The pipes 81 and 87 lead to annular spaces which are disposed outwardly with respect to the head 21, whereas, the pipes 83, 85 lead to annular spaces which aredisposed at the inner side of the pistons 69, 71. The introduction of a fluid pressure medium through the proper pipe, therefore, :will effect movement of an actuating ring along the ax-isin 'the desired direction. At the same time through another of these pipes the pressure previously introduced into an annular fluid pressure space may be exhausted as the actuating ring is moved.

As shown in Fig. 6' the left hand actuating ring 67 is in position toward the right and in engagementwith the pawls at the left side of the head 21. V The right hand actuating ring 67 is disposed toward the right and out of engagement with the corresponding pawls at the right side of the head 21. In order to secure these positions of the actuating rings the fluid pressure medium is supplied through a valve structure which comprises a rotary valve element 91, Figs. 1 and 2, having a cylindrical outer surface 93 fitting in a cylindrical bore 95 of a valve body 97. The rotary valve element 91 has a central passage 99 through which the fluid pressure medium under pressure may be supplied. In Fig. 6, as shown at B, the valve element 91 is in position with its port 101 in communication with the pipe 83 which is connected to the annular space at the left side of the right hand piston 69, 71. Correspondingly, in this position of the element 91 the pipe 81 communicates with the annular exhaust port 103 of the valve element, so that the fluid pressure medium from the right side of the right hand piston 69, 71 may be exhausted through the exhaust pipe 105.

When it is desired to move the right hand actuating ring toward the left to effect disengagement of the right hand set of pawls from the ratchet teeth 33, as shown in Fig. 7, the valve element 91 may be rotated to move the exhaust port 107 formed in the valve element 91 to the position shown at B in Fig. 7 to place the exhaust pipe 83 in communication with the exhaust 109. In this position the valve element 91 is disposed with the port 111 at A in communication with pipe 81, so that the fluid pressure medium from the supply 99 is carried to the right hand side of the actuating ring 67 in Fig. 7, to move this actuating ring toward the left to the position shown. The elongated exhaust port 103, as shown at A, remains in communication with the exhaust 105. The port 101 in the position of the valve element 91 in Fig. 7 as shown at B, now is sealed at the inner cylindrical surface 95 of the body. It thus will be clear, with the valve element 91 disposed in the two positions shown in Figs. 6 and 7, about 45 apart,'that the respective portions of the valve structure which are identified with the letters A and B will be effective to secure the two positions of the right hand actuating ring 67 out of engagement with the pawls in Fig. 6, and in engagement with these pawls in Fig. 7 to determine the direction ofrotation of the head relative to the ratchet ring.

Similarly, in Fig. 6, as shown at D, the port 115 of the valve element 91 is disposed in communication with the pipe 87 for supplying the fluid pressure medium to the left side of the piston formed by the left hand actuating ring 67 and its ribs 69 and packing 71. The actuating ring is thus forced toward the right to engage the left hand set of pawls by the pressure which is carried into the annular fluid pressure space at the left of the left hand actuating ring in Fig. 6. The fluid pressure medium from the right side of the left hand actuating ring 67 inFig. 6 is released through the pipe 85 to the elongated exhaust port 117 communicating with the exhaust pipe 119, as shown at Cin Fig. 6.

. To effect the movement of the right hand actuating ring 67 from the right handposition of Fig. 6 to the left hand position of Fig. 7, the rotary valve element 91 has been rotated counterclockwise about 45 to the position of Fig. 7. In such rotation of the rotary element 91 the exhaust port 107 moves into position to provide communication between the pipe 83 and the exhaust pipe 109 as shown at B in Fig. 7. In the movement referred to, the port 115, which has been in communication with the pipe 87, Fig. 6, will be moved counterclockwise to the closed position shown at D, Fig. 7, and theport 121 will be brought into communication with the pipe 87 to maintain fluid pressure at the left side of the piston 69, 71 of the left hand actuating ring 67. correspondingly, the exhaust port 117, because of its arcuate length will maintain communication between the pipe 85 and the exhaust pipe 119, as shown at C in Figs. 6 and 7.

:In Fig. 7 both actuating rings are in engagement with the respective pawls to hold the pawls of both sets out 6 of engagement with the ratchet teeth. The ratchet ring 33 and the head 21 thus are prevented from cooperating to efiect rotation of one with respect to the other. The drill thereby is not positively rotated under the action of the rifle bar.

In Fig. 8 the actuating rings 67 are shown in position to provide for reverse rotation with respect to that of Fig. 6. The right hand actuating ring 67, however, is in the same position as shown in Fig. 7 and the fluid pressure is supplied through the pipe 81 to the right side of the right hand actuating ring 67. This pressure is supplied from the central passage 99 through the port 123 shown at A, Fig. 8, in communication with the pipe 81, the rotary element 91 having been rotated counterclockwise about 45 from the position of Fig. 7 or from the position of Fig. 6. The port 111 thereby is moved out of register with the pipe 81' and closed at the inner surface 95 of the body 97. In this rotation the elongated exhaust port 107 also is rotated but, as shown at B, Fig. 8, remains in communication with the pipe 83 to exhaust the fluid pressure medium from the left side of the right hand actuating ring to the exhaust pipe 109.

In this rotation also the supply port becomes disposed in communication with the pipe 85, as shown at C, Fig. 8, to supply the fluid pressure medium to the right side of the piston of the left hand actuating ring 67 to move this actuating ring toward the left out of engagement with the adjacent set of pawls. At the same time, as shown at D, Fig. 8, the elongated exhaust port 127 is rotated into communication with the pipe 87 and the fluid pressure medium is exhausted from the left side of the left hand .ring 67 through pipe 87 and port 127 to the exhaust pipe 129. The valve control mechanism, therefore, is effective in Fig. 8 to maintain the right hand actuating ring in engagement with the right hand set of pawlsto disengage 'these pawls from the ratchet teeth and to maintain the left hand actuating ring 67 out of engagement with the adjacent pawls, so that these pawls are released to engage the ratchet teeth and to cooperate with the ratchet ring to produce the unidirectional relative movement of the head 21 and the ratchet ring 31 in the direction opposite to that which is secured in Fig. 6.

It will be understood, by constructing the control valve structure with the requisite additional ports, or by constructing the portions of this valve structure corresponding to the sections A, B, C, D so that these four portions may be operated independently of each other.

- As will be seen in Fig. 2, the dispositions of the supply ports and of the exhaust ports to provide the settings as described for control of the positions of the actuating rings may be secured by'forming the ports respectively in planes AA, BB, CC and DD that are spaced along the axis of the rotary element 91. The conduits shown diagrammatically in Figs. 6, 7 and 8 as pipes 81, 83, 85, 87 may be provided by channels formed by any suitable means in the walls of housing 11 or in other parts for establishing communication between the supply passage 99 and the respective sides of the pistons provided by the actuating rings 67 and for exhaust of the fluid pressure medium from each side of these pistons as above described.

As shown in Fig. 1 a pin 131 may be disposed in a hole in the housing and entering a corresponding depres sion in the ratchet ring 31. The pin 131 locks together the housing and the ratchet ring so that the positive rotation of the head in a selected direction is determined by operation of the actuating rings 67 in the manner de-' scribed. If the pin 131 is withdrawn, however, the ratchet ring is free to rotate relative to .the-housingand there sulting slip rotation may be secured incither "right or left hand rotation determinate upon the pawlengagement which is desirable for some drilling operations. In order to control the amount ofslip in the operation with slip rotation, the friction between the members 35', 37 and assess the corresponding surfaces on the cover 135 and on the housing 11 engaging these members is controlled by tension rods 137 connecting the cover 135 to the casing 15 and provided with nuts 139 which may be adjusted to adjust the tension of the rods 137.

As shown in Fig. 2, at the end of the element 91 a thumb lever 141 is secured to the element 91 by the nut 143-for rotating element 91. For the purpose of holding the element 91 in any one of the three positions described in connection with Figs. 6, 7 and 8 a detent pin 145 is mounted in the bore of a hub 147 of the cover 135 and held into engagement with a recess 149 in the element 91 by a compression spring 151.

Compressed air for operating the drill is connected to the drill through the pipe 153, Fig.- l, and may pass through a center bore 155 in the head 157 to reach the conventional control mechanism, not shown, for effecting the usual rapid reciprocating movement of the piston in the cylinder 13 for bringing successive impacts upon the drill. A passage 159 may be provided in the element 91 communicating with the pipe 153 or the center bore 155 in all positions to which the element is rotated for supplying the compressed air as the fluid pressure medium to the central passage 99 of the valve element 91.

Within the scope of the invention the structure disclosed in the drawings may be modified while maintaining the features of the invention with respect to the pawls supported by the head carried by the ride bar and disposed inwardly of the ratchet ring extending about the periphery of the head, thus securing the compact construction and providing for the actuation of the pawls by the actuating rings movable axially into and out of engagement with the'pawls, there rings being capable of being selectively moved by asuitable control means.

I' claim:

1. In a rock drill having a rifle bar for effecting rotational movement of the drill concomitantly with movement of the motor to and fro along the axis of the rifle bar, a head connected to said bar and having an outer periphery extending about said axis, and a ratchet ring extending about said head and providing ratchet teeth at the inner periphery of the ring adjacent said peripheryof said head, the combination with said head and said ratchetrring, of two pawls supported by said head for movement of said pawlsinto and out of engagement with the teeth of said ratchet ring, a given pawl being disposed so as to provide-for unidirectional rotation of said head relative to said ring in a given direction while preventing rotation in the reverse direction upon engagement of said given pawl with said teeth, the other of said pawls being disposed so as to provide for unidirectional rotation of said head relative to said ring in said reverse direction while preventing rotation of said head in said given direction upon engagement of said other pawl with said teeth, and means operatively connected to said two pawls and axially operable for selectively effecting engagement of said pawls with said ratchet teeth to provide for said unidirectional rotational movement of said head relative to said ratchet ring in selected directions.

, 2. in a rock drill the combination as defined in claim 1 which" comprises a housing, said rifle bar and head and said ratchet ring being supported in said housing for said rotational movements thereof, and locking means operable at will for. locking said ratchet ring to said housing.

3. In a rocicdrill having a rifle bar for effectingrrotational movement of the drill concomitantly with movement of'themotor to and fro along the axis of the rifie bar, a head connected to said bar and having an outer periphery extending about said axis, and a ratchet ring extending about. said head and providing ratchet teeth at the inner periphery of the ring adjacent said periphery of said head, the combination with said head and said ratchet ring, of two sets of pawls disposed in spaced relation to each other along said axis, the pawls in each set being disposed in spaced relation about the axis of said ratchet ring, the pawls of said two sets being dis.

posed so as to provide for unidirectional rotation ofsaid head relative to said ring in a given direction upon engagement of the pawls of a given set and for unidirectional rotation in the reverse direction upon engagement of the pawls of the other set while preventing rotation in the respective opposite directions, and means operatively connected to said two sets of pawls and axially operable for selectively effecting engagement of the pawls of said given and said other set with said ratchet teeth to provide for said unidirectional rotational movement of said rifle bar in selected directions.

4. In a rock drill the combination as defined in claim 3 in which said means operatively connected to said two sets of pawls comprises two actuating rings extending about said axis and each supported for movement thereof along said axis forwardly and revers'ely, and means operatively connecting said actuating rings respectively to said two sets of pawls for eifecting movement of said pawls out of and into engagement with said ratchet teeth respectivelyv upon said axial movement of said actuating rings in their respective forward and reverse directions.

5. In a rock drill the combination as defined in claim 3 in which said means operatively connected to said two sets of pawls comprises two cam rings extending about said axis and supported for movement thereof along said axis forwardly into engagement with the pawls of the respective sets to effect disengagement of said pawls from the teeth of said ratchet ring, said cam rings being reverseiy relative to one another movable along said axis to selectively engage the pawls of the respective sets to release said pawls of one of said two sets of pawls for engagement with said ratchet teeth.

6. In a rock drill thecombination as defined in claim 5 in which said cam rings respectively are formed to provide annular pistons extending about said axis, and means providing annular fiuid pressure spaces defined between cylindrical surfaces extending about said axis and cooperating respectively with said annular pistons of said cam rings for movement of said pistons along said axis. respectively within said annular spaces, and means operatively connected to said annular spaces for delivering thereto and exhausting therefrom a fluid pressure medium for selectively effecting said axial movements of said piston and cam rings in the direct-ions to effect said selective engagement of said cam rings with and disengagement from the pawls of said two sets of pawls.

7. In a rock drill having a rifle bar for effecting rotational movement of the drill concomitantly with move.- ment of the drill to and fro along the axis of the r'ifleibar, a head connected to said bar and having a generally cylindr-ical outer periphery coaxial with said bar, and a ratchet ring extending about said head generally coaxiallyi with said cylindrical periphery'thereof and providing ratchet teeth at the inner periphery of the ring adjacent said cylindrical periphery of said head, the combination with said head and ratchet ring, of two sets of pawls disposed in spaced relation to each other along said axis, the

pawls in each set being disposed in spaced relation about the axis of said bar and supported in recesses formed in said head for pivotal movement of said pawls into and out of engagement with the teeth of said ratchet ring, the pawls of one set being disposed for engagement with said teeth so as to provide 'for unidirectional rotation of said head relative to saidring in a given direction and to prevent rotation in the reverse direction, thepawls of the other set being disposed for engagement with saidteeth so as to provide for unidirectional rotation'oi said head relative to said ring in said'reverse direction and to prevent rotation in said given direction, members disposed at opposite sides of said head in spaced relation with said head and said ratchet ring to provide walls assess? defining annular fluid pressure spaces disposed respectively adjacent the ends of the ratchet teeth of said ratchet ring, actuating rings respectively disposed within said annular fluid pressure spaces and having camming portions projecting from said spaces respectively axially toward said two sets of pawls, means cooperating with said actuating rings and the Walls of said annular spaces to confine a fluid pressure medium in relation to said actuating rings as pistons in said spaces, and fluid control means connected to said annular spaces at the respective axially spaced sides of said pistons and operable for selectively effecting axial movement of said pistons to move said camming portions into and out of engagement with the pawls of the respective sets, whereby upon selective operation of said control means unidirectional rotational movement of said rifle bar in a selected direction may be efiected and said rifle bar may be effective in both directions upon operation of said control means to effect disengagement of both sets of pawls.

8. In a rock drill having a rifle bar for effecting rotational movement of the drill concomitantly with movement of the drill to and fro along the axis of the rifle bar, a head connected to said bar and having a generally cylindrical outer periphery coaxial with said bar, and a ratchet ring extending about said head generally coaxially with said cylindrical periphery thereof and providing ratchet teeth at the inner periphery of the ring adjacent said cylindrical periphery of said head, the combination with said head and ratchet ring, of two sets of pawls disposed in spaced relation to each other along said axis, said head having oppositely facing surfaces disposed in planes transverse to said axis of the rifle bar and extending from said rifle bar outwardly to said cylindrical periphery of said head, the pawls in each set being disposed in spaced relation about the axis of said bar outwardly from said axis and supported in recesses formed in said head inwardly with respect to said transverse surfaces thereof for pivotal movement of said pawls into and out of engagement with the teeth of said ratchet ring, the pawls of one set being disposed for engagement with said teeth so as to provide for unidirectional rotation of said head relative to said ring in a given direction and to prevent rotation in the reverse direction, the pawls of the other set being disposed for engagement with said teeth so as to provide for unidirectional rotation of said head relative to said ring in said reverse direction and to prevent rotation in said given direction, closing members disposed at opposite sides of said head respectively adjacent said transverse surfaces of said head, said closing members engaging said ratchet ring adjacent axially spaced ends thereof, said closing members and said ratchet ring providing concentric cylindrical surfaces coaxial with said rifle bar and defining therebetween annular fluid pressure spaces disposed in axially spaced relation to each other and respectively adjacent the ends of the ratchet teeth of said ratchet ring, actuating rings respectively disposed within said annular fluid pressure spaces and having camming portions projecting from said spaces respectively axially toward said two sets of pawls, means cooperating with said actuating rings and said cylindrical walls of said annular spaces to confine a fluid pressure medium in relation to said actuating rings as pistons in said spaces, and fluid control valves and conduits connected to said annular spaces at the respective axially spaced sides of said pistons and operable for selectively elfecting axial movement of said pistons to move said camming portions into and out of engagement with the pawls of the respective sets, whereby upon selective operation of said valves unidirectional rotational movement of said rifle bar in a selected direction may be effected and said rifle bar may be released for rotational upon operation of said valves to effect disengagement of both sets of pawls.

9. In a device for controlling the rotational movement of a rock drill having a rifle bar, and a member cooperating with the rifling thereof for effecting rotation of said bar concomitantly with movement of said member to and fro along the axis of the bar, the combination with a head adapted to be connected to said bar for rotation therewith on the axis of the bar, said head having a periphery generally coaxial with said bar, and a ratchet ring extending about said head and providing ratchet teeth at the inner periphery of said ring adjacent the periphery of said head, of two sets of pawls disposed in spaced relation to each other along said axis, the pawls of each set being disposed in spaced relation about said axis and sup ported by said head for movement thereof into and out of engagement with the teeth of said ratchet ring, the pawls of a given set being disposed for engagement with said teeth to provide for unidirectional rotation of said head relative to said ring in a given direction and to prevent rotation in the reverse direction, the pawls of the other set being disposed for engagement with said teeth to provide for unidirectional rotation of said head relative to said ring in said reverse direction and to prevent rotation in said given direction, cam rings coaxial with said ratchet teeth and supported for movement of said cam rings along said axis respectively into engagement with the pawls of the respective sets to effect disengagement of said pawls from said ratchet teeth and for movement of said cam rings out of engagement with the pawls of the respective sets to release said pawls for engagement with said ratchet teeth, and means operatively connected to said cam rings for selectively effecting engagement of said cam rings with the respective sets of pawls to disengage the pawls of the respective sets from said ratchet ring teeth to determine the direction of rotation of said head relative to said ratchet ring concomitantly with relative axial movement between said rifle bar and said member of said drill cooperating therewith.

10. In a rock drill the combination as defined in claim 1, including friction means engaging said ratchet ring and locking means adapted to engage said friction means and said ratchet ring to prevent rotation thereof, said locking meansadapted to release said friction means and ratchet ring to provide rotation of such ratchet ring relative to said friction means and against the frictional forces thereof in a direction dependent upon the selective engagement of said pawls with said ratchet teeth.

References Cited in the file of this patent UNITED STATES PATENTS 

